In accordance with widespread use of lead-wire less electronic components, namely, so-called chip components, components vary in shape and size. Since an electronic circuit is constituted by combining such electronic components, a much higher speed and a high reliability are demanded to be secured for electronic component mounting apparatuses which fix the electronic components to printed boards.
A plurality of the electronic component mounting apparatuses of the type referred to above are generally used in order to mount the electronic components to many printed boards. Since a loading operation of the printed board takes place for each component mounting apparatus when a plurality of the component mounting apparatuses are employed for one board transfer path, there is a problem that a degree of increase in production efficiency lowers as compared with a degree of increase in a number of apparatuses to be set. Suppose, for example, that a board loading time at each component mounting apparatus is 4 seconds and a mounting time of all electronic components is 10 seconds, then one component mounting apparatus requires 14 (10+4) seconds and two component mounting apparatuses require 9 (10/2)+4) seconds to produce one complete board.
The applicant of the present invention has disclosed an invention as a technique for solving the above problem in a publication of unexamined patent application of JP, 10-256785, A. A constitution and an operation of a printed board transferring apparatus disclosed in the published application of the above JP, 10-256785, A will be described below with reference to FIG. 9.
Roughly speaking, a component mounting apparatus 1 shown in FIG. 9 comprises two mounting parts 2A, 2B arranged in series, moving devices 3A, 3B for boards to be mounted, which are set respectively to the mounting parts 2A, 2B, a carry-in device 4 for supplying unmounted boards 7 to the mounting parts 2A, 2B, and a carry-out device 5 for transferring mounted boards 8 sent out from the mounting parts 2A, 2B. Although the carry-in device 4 and the carry-out device 5 are illustrated as if arranged in parallel in the same plane in FIG. 9 to facilitate a graphic representation and description, and moreover understanding, the carry-out device 5 and the carry-in device 4 are actually placed in an overlapping manner so as to be arranged on upper and lower sides to make the apparatus compact.
The moving devices 3A, 3B for boards to be mounted have loader conveyors 31A, 31B which reciprocate between the carry-in device 4 and the mounting parts 2A, 2B to supply unmounted boards 7 from the carry-in device 4 to the mounting parts 2A, 2B, and unloader conveyors 32A, 32B which reciprocate between the mounting parts 2A, 2B and the carry-out device 5 to send out mounted boards 8 from the mounting parts 2A, 2B to the carry-out device 5. Since the carry-in device 4 and the carry-out device 5 are set in an overlapping manner in an up-down direction as mentioned above, the loader conveyors 31A, 31B move slantwise along a first direction 10 orthogonal to a board transfer direction 9, while the unloader conveyors 32A, 32B, positioned at an equal height as that of the carry-out device 5, move at this height in a second direction 11.
The component mounting apparatus 1 constituted as above operates in a manner to be described below.
When the mounting part 2A is not operating, an unmounted board 7 transferred by the carry-in device 4 from upstream equipment (not shown) is carried by the loader conveyor 31A into the mounting part 2A, and then all electronic components are mounted onto the unmounted board 7 at the mounting part 2A. A mounted board 8 with the components mounted thereon is carried by the unloader conveyor 32A to the carry-out device 5 and then transferred by the carry-out device 5 to equipment of a next process.
If the mounting part 2A is operating, the unmounted board 7 is transferred by the carry-in device 4, to pass a section of the mounting part 2A, to the mounting part 2B. When the mounting part 2B is not operating at this time, the unmounted board 7 is carried into the mounting part 2B by the loader conveyor 31B, and then all electronic components are mounted onto the unmounted board 7 by the mounting part 2B. A mounted board 8 with the components mounted thereon is sent out by the unloader conveyor 32B to the carry-out device 5 and transferred by the carry-out device 5 to next process equipment.
In producing one mounted board 8 in the component mounting apparatus 1 as described above, a loading operation of boards to the mounting parts 2A, 2B is completed at a time irrespective of a number of mounting parts. In other words, boards 7 can be supplied independently to each of the mounting parts 2A, 2B because of presence of the carry-in device 4 and the carry-out device 5. Given, for instance, that a board loading time and a mounting time at each of the mounting parts 2A, 2B are 4 seconds and 10 seconds, respectively, and since boards 7 can be supplied and equipped with components at the same time at the mounting parts 2A, 2B, a line Tact necessary for producing one finished board becomes (10+4)/2, i.e. 7 seconds, and shortened by 2 seconds in comparison with the earlier-mentioned 9 seconds.
The invention disclosed by the published application of the above JP, 10-256785, A is aimed to provide a board transfer method whereby a production efficiency of an electronic component mounting apparatus can be improved by shortening a loading time per board sent out from component mounting apparatus 1 on an understanding that each mounting part 2A, 2B can mount all necessary electronic components for producing one mounted board 8. However, as in recent years, a production form, in which a volume of production is relatively low and there are a wide variety of products to be made, is frequently practiced. Therefore, a condition that all of electronic components are mounted by one mounting part without fail is difficult to maintain.
Concretely, in a case, for example, where a number of types of electronic components necessary for manufacturing one mounted board 8 is more than a number of types of components which one mounting part can provide, all electronic components cannot be mounted by the one mounting part. In such a case as this, there is a problem in that it is necessary to set another component mounting apparatus, having another constitution, in order to mount remaining components.
The present invention is devised to solve the above problems and has for its object to provide a board transferring apparatus and method, and a component mounting apparatus which can improve a production efficiency in accordance with types of boards to be produced.